test: add tests for addAsyncToFunctionFix rule

Author: y-hsgw

tests/lib/utils/add-async-fo-function-fix.test.ts

@@ -0,0 +1,119 @@
+import { createTestingLibraryRule } from '../../../lib/create-testing-library-rule';
+import { addAsyncToFunctionFix } from '../../../lib/utils/add-async-fo-function-fix';
+import { createRuleTester } from '../test-utils';
+
+import type { TSESTree } from '@typescript-eslint/utils';
+
+type MessageIds = 'alwaysAsync';
+
+const rule = createTestingLibraryRule<[], MessageIds>({
+	name: __filename,
+	meta: {
+		docs: {
+			recommendedConfig: {
+				dom: 'error',
+				angular: 'error',
+				react: 'error',
+				vue: 'error',
+				svelte: 'error',
+				marko: 'error',
+			},
+			description: 'Fake rule for testing addAsyncToFunctionFix',
+		},
+		messages: { alwaysAsync: 'Function should be async' },
+		schema: [],
+		fixable: 'code',
+		type: 'problem',
+	},
+	defaultOptions: [],
+	create(context) {
+		const reportIfNotAsync = (
+			node:
+				| TSESTree.FunctionExpression
+				| TSESTree.FunctionDeclaration
+				| TSESTree.ArrowFunctionExpression
+		) => {
+			if (!node.async) {
+				context.report({
+					node,
+					messageId: 'alwaysAsync',
+					fix(fixer) {
+						return addAsyncToFunctionFix(
+							fixer,
+							fixer.insertTextBefore(node, ''),
+							node
+						);
+					},
+				});
+			}
+		};
+		return {
+			FunctionExpression: reportIfNotAsync,
+			ArrowFunctionExpression: reportIfNotAsync,
+			FunctionDeclaration: reportIfNotAsync,
+		};
+	},
+});
+
+const ruleTester = createRuleTester();
+
+ruleTester.run(addAsyncToFunctionFix.name, rule, {
+	valid: [
+		{ code: 'async function foo() {}' },
+		{ code: 'const bar = async function() {}' },
+		{
+			code: `
+			async function foo(a, b) {
+				return a + b;
+			}`,
+		},
+	],
+	invalid: [
+		{
+			code: 'const bar = function() {}',
+			output: 'const bar = async function() {}',
+			errors: [{ messageId: 'alwaysAsync' }],
+		},
+		{
+			code: 'const bar = () => {}',
+			output: 'const bar = async () => {}',
+			errors: [{ messageId: 'alwaysAsync' }],
+		},
+		{
+			code: `
+			function foo(a, b) {
+  			return a + b;
+			}`,
+			output: `
+			async function foo(a, b) {
+  			return a + b;
+			}`,
+			errors: [{ messageId: 'alwaysAsync', line: 1 }],
+		},
+		{
+			code: `
+			const bar = async function() {}
+			const foo = function() {}
+			`,
+			output: `
+			const bar = async function() {}
+			const foo = async function() {}
+			`,
+			errors: [{ messageId: 'alwaysAsync', line: 3 }],
+		},
+		{
+			code: `
+			const bar = function() {}
+			const foo = function() {}
+			`,
+			output: `
+			const bar = async function() {}
+			const foo = async function() {}
+			`,
+			errors: [
+				{ messageId: 'alwaysAsync', line: 2 },
+				{ messageId: 'alwaysAsync', line: 3 },
+			],
+		},
+	],
+});